Example 5.23 Charge separation on FAAQ
$molecule 0 1 C -0.64570736 1.37641945 -0.59867467 C 0.64047568 1.86965826 -0.50242683 C 1.73542663 1.01169939 -0.26307089 C 1.48977850 -0.39245666 -0.15200261 C 0.17444585 -0.86520769 -0.27283957 C -0.91002699 -0.02021483 -0.46970395 C 3.07770780 1.57576311 -0.14660056 C 2.57383948 -1.35303134 0.09158744 C 3.93006075 -0.78485926 0.20164558 C 4.16915637 0.61104948 0.08827557 C 5.48914671 1.09087541 0.20409492 H 5.64130588 2.16192921 0.11315072 C 6.54456054 0.22164774 0.42486947 C 6.30689287 -1.16262761 0.53756193 C 5.01647654 -1.65329553 0.42726664 H -1.45105590 2.07404495 -0.83914389 H 0.85607395 2.92830339 -0.61585218 H 0.02533661 -1.93964850 -0.19096085 H 7.55839768 0.60647405 0.51134530 H 7.13705743 -1.84392666 0.71043613 H 4.80090178 -2.71421422 0.50926027 O 2.35714021 -2.57891545 0.20103599 O 3.29128460 2.80678842 -0.23826460 C -2.29106231 -0.63197545 -0.53957285 O -2.55084900 -1.72562847 -0.95628300 N -3.24209015 0.26680616 0.03199109 H -2.81592456 1.08883943 0.45966550 C -4.58411403 0.11982669 0.15424004 C -5.28753695 1.14948617 0.86238753 C -5.30144592 -0.99369577 -0.39253179 C -6.65078185 1.06387425 1.01814801 H -4.73058059 1.98862544 1.26980479 C -6.66791492 -1.05241167 -0.21955088 H -4.76132422 -1.76584307 -0.92242502 C -7.35245187 -0.03698606 0.47966072 H -7.18656323 1.84034269 1.55377875 H -7.22179827 -1.89092743 -0.62856041 H -8.42896369 -0.10082875 0.60432214 $end $rem JOBTYPE FORCE METHOD B3LYP BASIS 6-31G* SCF_PRINT TRUE CDFT TRUE $end $cdft 2 1 1 25 -1 26 38 $end
The value of 2 under $cdft section in the FAAQ example represents the constraint. The valules,
1 and -1, represent the coefficients for fragment charges. Suppose the first fragment consists of atom 1–25
with A excess electrons, and the second fragment consists of atom 26–38 with B excess electrons.
The $cdft section can be viewd as a system of linear equations as follows:
The second equation is zero because the FAAQ is neutral. by solving the system of linear equations, one gets A = 1, and B = -1. However, the $cdft section is equivalent to the following one.
$cdft 1 1 1 25 -1 1 26 38 $end
Example 5.24 Cu2-Ox High Spin
$molecule 2 3 Cu 1.4674 1.6370 1.5762 O 1.7093 0.0850 0.3825 O -0.5891 1.3402 0.9352 C 0.6487 -0.3651 -0.1716 N 1.2005 3.2680 2.7240 N 3.0386 2.6879 0.6981 N 1.3597 0.4651 3.4308 H 2.1491 -0.1464 3.4851 H 0.5184 -0.0755 3.4352 H 1.3626 1.0836 4.2166 H 1.9316 3.3202 3.4043 H 0.3168 3.2079 3.1883 H 1.2204 4.0865 2.1499 H 3.8375 2.6565 1.2987 H 3.2668 2.2722 -0.1823 H 2.7652 3.6394 0.5565 Cu -1.4674 -1.6370 -1.5762 O -1.7093 -0.0850 -0.3825 O 0.5891 -1.3402 -0.9352 C -0.6487 0.3651 0.1716 N -1.2005 -3.2680 -2.7240 N -3.0386 -2.6879 -0.6981 N -1.3597 -0.4651 -3.4308 H -2.6704 -3.4097 -0.1120 H -3.6070 -3.0961 -1.4124 H -3.5921 -2.0622 -0.1485 H -0.3622 -3.1653 -3.2595 H -1.9799 -3.3721 -3.3417 H -1.1266 -4.0773 -2.1412 H -0.5359 0.1017 -3.4196 H -2.1667 0.1211 -3.5020 H -1.3275 -1.0845 -4.2152 $end $rem METHOD B3LYP BASIS 6-31G* SCF_PRINT TRUE CDFT TRUE $end $cdft 2 1 1 3 s -1 17 19 s $end
Example 5.25 Constrained DFT with FBH charges applied to FHO interaction
$molecule -1 1 -- -1 1 F 1.2344377204 -0.0287603388 0.0000000000 -- 0 1 O -1.2152661043 0.1159898799 0.0000000000 H -0.1545755250 0.1042552996 0.0000000000 H -1.3911772011 -0.8334364448 0.0000000000 $end $rem METHOD hf BASIS aug-cc-pvtz XC_GRID 3 CDFT true CDFT_POP fbh NO_REORIENT true POINT_GROUP_SYMMETRY false INTEGRAL_SYMMETRY false $end $cdft 1.0 1 1 1 0.0 1 1 1 s $end